Expression of peroxisome proliferator-activated receptor-gamma coactivator-1 β (PGC-1β) is upregulated in synovium in rheumatoid arthritis (RA). (A) Intensive synovial PGC-1β expression in synovium of a RA patient. (B) Moderate synovial PGC-1β expression in synovium of an osteoarthritis (OA) patient. (C) Mild synovial PGC-1β expression in synovium of an orthopedic arthropathy (Orth.A) patient. (D) Percentage of lining PGC-1β + cells in RA, OA and Orth.A patients. A, B, C: original magnification × 400. The data are represented by median ± IQR. **P <0.01, ***P <0.001.